Polyphosphate phenyl esters containing isocyanate radicals



United States Patent No Drawing. Filed Oct. 6, 1961, Ser. No. 143,284 3 Claims. (Cl. 260-461) This invention relates to aromatic isocyanates and more particularly to isocyanato aromatic esters, thioesters and amide derivatives of phosphoric acid and thiophosphoric acids. 7

This application is a continuation-in-part of co-pending applications Serial Nos. 789,810 filed January 29', 1959, now Patent No. 3,013,048 and 799,449 filed March 16, 1959, now Patent No. 3,054,756.

It is an object of this invention to provide isocyanato aromatic phosphoric acid and thiophosphoric acid derivatives. Another object of this invention is to provide isocyanato aromatic phosphoric acid and thiophosphoric acid derivatives which may be used to prepare urethanes having improved flame resistance. Still another object of this invention is to provide a process for the preparation of aryl isocyanato phosphoric acidand thiophosphoric acid derivatives.

These objects and others, which will become apparent from the following disclosure, are accomplished in accordance with the invention, generally speaking, by providing isocyanato aryl derivatives of phosphoric acids. Thus, this invention contemplates isocyanato arylphosphorous esters, thioesters and amides having the formula ',4"-triisocyanato phenyl phosphate L QNOOI i 4,4',4"-triisocyanato phenyl thiophosphate -4,4',4"-triisocyanato benzyl phosphate P- o-crn-Q-nc o] 4,4,4-triisocyanato benzyl thiophosphate Diethy1-4-isocyanatophenyl phosphoric acid tries'ter 3,136,806 Patented June 9, 1964 ice Diethyl-4-isocyanatophenyl thiophosphoric acid triester Cyclopentadienyl-4-isocyanatophenyl phosphoric acid diester, dimethyl amide Cyclopentadienyl-4-isocyanatophenyl thiophosphoric acid diester dimethyl amide Eth'yl, vinyl, 4-isocyanato naphthyl phosphoric acid triester Ethyl, vinyl, 4-isocyanato naphthyl thiophosphoric acid triester i H5CqO-?OO:H3

Ethyl phosphoric acid ester-bis (N-methyl-N-4-isocyanatophenyl amide) acid ester-bis(N-methyl-N-4-iso- Ethyl thiophosphoric (3-isocyanato-5-methyl phenyl) phosphoric acid triester NCO (3-isocyanato-5-methyl phenyl) thiophosphoric acid triester IIICO i (3-isocyanato-5-methyl phenyl) dithiophosphoric acid triester CH] NCO 4,4',4"-triisocyanatophenyl dithiophosphate 4,4',4"-triisocyanatophenyl tetrathiophosphate 4-isocyanato, 6-chlorophenyl diethyl phosphoric acid triester 4-isoeyanato, 6-chlorophenyl diethyl thiophosphoric acid triester 4,4',4"-triisocyanato benzyl dithiophosphate The substituents in the above-mentioned formula may also contain further substituents such as, for example, halogen such as chlorine, iodine, and bromine; alkoxy such as methoxy, ethoxy and propoxy; carboxylic acid ester such as carbomethoxy, carboethoxy and carbobutoxy, and unsaturated hydrocarbon such as vinyl, allyl and butenyl, in addition to the isocyanato group which is attached to a carbon atom of an aromatic ring. Further, compounds containing more than one phosphoric acid or thiophosphoric acid nucleus are contemplated by the invention. In such cases R and R" in the foregoing formula may represent radicals of polyhydric alcohols such as, for example, ethylene glycol, Lil-propylene glycol, 1,4-butylene glycol and the like, polyvalen't amines such as, for example, N,N-dimcthyl ethylene diamine, N,N-diethyl 1,3 propylene diamine, N,N-dimethyl-l,3- phenyiene diamine and the like, linear or branched polyesters such as, for example, the reaction product of succinic acid with trimethylolpropane or ethylene glycol and the like, polycthers such as, for example, those obtained from the condensation of alkylene oxides and compounds such as diethylene glycol, polyamides, polyester amides such as, for example, the reaction product of succinic acid with amino alcohols and more particularly l-amino, Z-hydroxy ethylene and the like and polythioethers such as, for example, thioglycols and more particularly thiodiglycol which link two or more phosphoric acid or thiophosphoric acid nuclei through oxygen, sulfur and/or nitrogen atoms. Representative compounds of this type contemplated by the invention are, for example, those having the following formulae:

Phenyl phosphoric acid esters bis (N,N- 4 -isocyanato phenyl amide) S-methyl phenyl amide) IIICO NCO [ Q l Ql Thus, these compounds may be represented by the formula ii/ R-P RI! wherein R, X and R" have the meanings set forth above and R represents radicals which contain additional phosphorous containing entities according to the above specific formulas. These phosphorous containing entities which may be R may be represented by the formula wherein Y is a polyvalent radical obtained by removing two or more active hydrogen atoms from the active hydrogen containing groups of a polyhydric alcohol or polyamine, n is an integer of from 1 to 2 and z is an integer of from 1 to 2 which corresponds to the valence of Y less one. Therefore, the radicals R and R" may be replaced in the polymeric compounds so that all of the radicals attached to the central phosphorous atom contain additional phosphorous atoms or one or more of these radicals may be replaced by the polymeric radicals containing additional phosphorous atoms.

The new isocyanates are prepared by phosgenating the corresponding amino aryl phosphoric acid derivatives. The amino aryl phosphoric acid derivatives may be prepared by nitration followed by reduction of the corresponding phosphoric acid and thiophosphoric esters, thioesters and amides, such as, for example, triphenyl phosphate, tricresyl phosphate, triphenyl thiophosphate, triphenyl phosphoramide and the like. Further, the amino derivatives which are phosgenated in accordance with the process of 'thisinvention to prepare the new aromatic isocyanates may be prepared by the reaction of phos phoric acid chlorides or substituted phosphoric acid chlorides with nitrophenols and the like, such as, for example, nitro benzyl alcohol, .nitro naphthol and nitro methylphenol followed by reduction to the corresponding amines. The following examples illustrate the preparation of representative amino aromatic phosphoric acid and thiophosphoric acid derivatives which may be phosgenated in accordance with the process of the present invention.

Example 1 About 461 g. (1 mol) of p-nitrophenyl-phosphoric acid-triester, prepared by nitration of triphenyl phosphate in nitric acid (density 1.51) at about 5 C. to about 0 C. are dissolved in about 3000 cc. of methanol and introduced into a 7-liter stirrer-type autoclave after adding about 25 g. of fresh Raney nickel. The reduction is completed after about 2-3 hours at a temperature of about 50 C. and a hydrogen pressurebetween about 20 and about 40 atm.

In Working up the product, the reaction mixture is filtered while heating, from the hydrogenation catalyst and the filtrate is cooled with ice. About 105 g. of the p-aminophenyl-phosphoric acid-triester are crystallized out in the form of small needles. After filtering with suction, the remainder of the amino-compound is obtained by precipitation with water, whereby about another 210 g. crystallize out, so that the total yield is about 315 g. (85% of the theoretical). in this way the substance is obtained in an analytically pure form having sharp melting point. It can be recrystallized from alcohol and is completely soluble in 10% hydrochloric acid and has a melting point of 155 C.

Analysis.-Calculated: C, 58.3%; H, 4.86%; N,

11.31%; P, 8.36%. Found: C, 58.13%; H, 5.0%; N,

Example 2 About 195 g. of p-nitrophenyl-thiophosphoric acidtriester, prepared from nitrophenol sodium plus PSCl in xylene (M.P. 181 C.-183 C.) are dissolved in 1.2 liters of methanol and, after adding about 30 g. of Raney nickel, are hydrogenated at a temperature of about 50-75 C.

and at a hydrogen pressure of about 20-40 atm. The,

absorption of hydrogen is complete after two hours. After filtering, the main quantity of the p-aminophenyl-thiophosphoric acid-triester crystallizes out from the methanol, and the remainder can be obtained by precipitation with water. Yield: 132 g. (97.5% of the theoretical): M.P. 156 C.

Analysis.-Calculated for C H O N PS: C=56.0%,

H=4.6%, N=10.8%, S=8.2%, P=8.0%. Found: C=55.6%, H=4.9%, N=10.8%, S=8.2%, P=8.2%.

Example 3 About 95 g. of diethyl p nitrophenyl-thiophosphoric acid triester,-dissolved in about 300' cc. of methanol, are hydrogenated in the presence of about 25 g. of Raney nickel at between about 50 and about 60 C. and under a hydrogen pressure of about 2040 atm. The hydrogen absorption is complete after three hours. Thereafter, the solid material is filtered oil from the catalyst and the methanol solution is concentrated. The residue is a reddish-yellow oil which is completely soluble in 10% hydrochloric acid. Yield: 86 g.

Analysis. Calculated: N 5.7%, S 13.0%, P 12.0%. Found: N 5.56%, S 12.0%, P 12.6%. Analysis of the phenyl urea (M.P. 108 0.): Calculated, N=7.7%, S=8.8%, P=8.5%. Found, N=7.8%, S: 8.3%, P=8.5%.

Example 4 hours; the solid material is filtered off from the catalyst and the filtrate is concentrated. A light yellow oil which crystallizes on stirring with methylene chloride is left. Yield: 258 g., M.P. 101 C.l03 C. (with decomposition).

Analysis. Calculated: C 54.6%, H 5.8%, N 13.7%, P 10.1%. Found: C 54.6%, H 5.8%, N=14.2%, P: 10.1%.

Example 5 About 268 g. of p-nitrophenyl-phosphoric acid-diester methyl phenylamide (prepared according to Example 4) are hydrogenated and worked up as in Example 4. Yield: 220' g., M.P. C.111 C.

Analysis. -Calculated: C 61.9%, H 5.4%, N 11.4%, P=8.4%. Found: C=61.9%, H=5.7%, N: 11.7%, P=8.S%.

The amino compounds used as starting materials in the process of this invention are more particularly disclosed in co-pending application Serial No. 790,034.

According to the process of the invention, amino aryl phosphoric acid derivatives or amino aryl thiophosphoric acid derivatives are converted to the corresponding isocyanates by phosgenation. Any suitable phosgenation method may be used, such as, for example, the cold phasehot phase phosgenation or even according to the hydrochloride process, the corresponding amine hydrochloride being phosgenated. A suitable phosgenation process is disclosed in US. Patent 2,680,127. The process can be carried out either continuously or intermittently. Advantageously, one employs an inert solvent, such as, toluene,

benzene, xylylene, trichloroethylene, chlorobenzene, o-

dichlorobenzene. The temperature for the phosgenation reaction is not critical. However, it is preferable not to choose too high a temperature for the phosgenation. For this reason, the cold phase-hot phase phosgenation is preferred to the hydrochloride process. In the cold phasehot phase phosgenation, the mixture of earbamic acid chloride and amine hydrochloride occurs in such a fine suspension that the hot phase phosgenation is completed in a short time. Temperatures between about 80 C. and about C. are preferred in the final phase of the phosgenation, although higher and lower temperatures may be used, if desired.

Recrystallization or distillation of the isocyanates prepared according to the process of this invention is not necessary in most cases, since the products are obtained in a relatively pure form. However, any carbamic acid chloride which may still be present should be destroyed. The excess phosgene may be adequately removed by heating the reaction mixture for a short time at reduced pressure below the boiling point or by blowing an inert gas through the reaction mixture at an elevated temperature.

It was not to be expected that the phosgenation of the amino aryl phosphoric acid ester derivatives and the like would proceed without cleavage of the ester, thioester or amide bonds. However, the process of the invention proceeds in a surprisingly simple and convenient manner. The isocyanato aryl phosphoric acid derivatives are obtained in unexpectedly high yields usually exceeding 80% of the theoretical. The formation of acid chlorides which would be expected from the reaction of phosgene does not take place. Further, the acid chlorides do not appear as secondary products even in small quantities.

In order to better describe and further classify the invention, the following are specific embodiments.

Example 6 About 1.5 liters of substantially anhydrous chlorobenzene are placed in a three-liter flask, cooled to about 10 C. and thereafter about 800 g. of phosgene are in troduced and condensed. At the same temperature about 371 g. of finely powdered 4,4,4"-triamino-triphenyl phosphate are added in portions. The mixture is stirred for about four hours in the cold and then left overnight at room temperature. Thereafter, a powerful stream of phosgene is introduced at a temperature of between about 90 C. and about 110 C. until a homogeneous solution is present. The chlorobenzene solution is then blown out with nitrogen and the chlorobenzene distilled off in vacuo. The residue is thereafter treated for approximately another hour at about 160 C. under high vacuum in order to destroy remaining traces of carbamic acid chloride.

The yellow oil which remains is 4,4',4"-triisocyanatophenyl phosphate. It crystallizes after a few days as an analytically-pure white waxy mass. Yield: 380 g. (85% of the theoretical).

. Analysis-Calculated: C, 56.1%; H, 2.68%; N, 9.36%; P, 6.91%; NCO, 28.1%. Found: C, 55.74%; H, 2.60%; N, 9.70%; P, 6.95%; NCO, 28.3.

Example 7 About 354 g. of p-aminophenyl-thiophosphoric acid-triester are slowly introduced at a temperature of between about minus C. and about 0 C. into a solution of about 600 g. of phosgene in about 2.5 liters of chlorobenzene and the mixture is left standing overnight in the cold. The temperature is thereafter raised with further introduction of phosgene. After about 6 hours, at a phosgenation temperature of about 100 C. to about 110 C. everything dissolves except for a slight slimy residue, which is filtered off following addition of substantially anhydrous active carbon. A light-yellow melt, 4,4'4"-triisocyanato phenyl thiophosphate, is left, which soon solidifies into crystalline form. Yield 380 g. (82% of the theoretical), M.P. 84 C.86 C.

Analysis. Calculated: C=54.1%, H=Z.6%, N=9.05%, P=6.7%, S=6.9%. Found: C=53.9%, H=2.8%, N=9.1%, P=6.9%, S=7.3%.

Example 8 About 700 g. of phosgene are liquified in about 1.5 liters of chlorobenzene at about C. Thereafter, a solution of about 475 g. of diethyl mono-p-aminophenylthiophosphoric acid-triester, dissolved in about 1 liter of chlorobenzene, is added dropwise so that the temperature does not rise higher than about 0 C. After standing in the cold overnight, more phosgene is introduced at about 100 C. to about 110 C. A light clear solution has formed after about 4 hours. This is worked up as in Example 2. About 472 g. of the slightly brownish oily isocyanate are obtained as residue. B.P.: 147 C149 C. (with slight decomposition).

Analysis. Calculated: N=5.2%, P=11.4%, S=11.8%. Found: N=5.3%, P=l1.0%, S=1l.0%.

Example 9 C=59.8%, H=3.8%, Found: C=59.9%, H=3.8%,

aralkyl, S-alkaryl,

8 Example 10 About 1 moi of a p-nitrophenyl phosphoric acid ester prepared by the nitration of the phenyl ester of phosphoric acid having the formula at about 5 C. to about 0 C. is dissolved in about 3000 cc. of methanol and introduced into a 7 liter stirrer-type autoclave after adding about 25 grams of fresh Raney nickel. The reduction is completed after about 3 hours at a temperature of about 50 C. and a hydrogen pressure of between about 20 and 40 atmospheres. The corresponding amino phenyl phosphoric acid ester is obtained. This amine is then reacted with an excess of phosgene under substantially anhydrous conditions in chlorobenzene by cooling the chlorobenzene solution of the amine to about 10 C. and introducing about 800 grams of phosgene which had been previously dissolved in chlorobenzene and cooled to about 10 C. The mixture is stirred for about 4 hours and then left overnight at room temperature. Thereafter, a powerful stream of phosgene is introduced at a temperature of between about C. and about C. until a homogeneous solution results. The chlorobenzene is then removed and the residue is treated for about 1 hour at about C. under high vacuum to destroy the carbamic acid chloride. The resulting product is the isocyanato phosphorous compound having the formula Although only some of the aforementioned isocyanato aryl phosphoric acid and thiophosphoric acid derivatives were prepared in the foregoing examples, it is to be understood that any of the class of phosphoric acid derivatives more fully disclosed above can be prepared in a similar manner. Further, any of the corresponding amino compounds, more fully disclosed above can be phosgenated in accordance with the process disclosed by the examples to produce the corresponding isocyanato aryl phosphoric acid derivatives.

It is obvious that the process of the invention may be used to produce monoisocyanates, diisocyanates, triisocyanates or higher polyisocyanates. The monoisocyanates and polyisocyanates obtainable by the process of the present invention are useful as starting materials for the manufacture of polyurethane plastics. They may be polymerized by the well-known isocyanate polyaddition process to prepare cellular polyurethanes or homogeneous polyurethanes having improved flame resistance. Coatings produced from the isocyanates of the present invention may be used to replace oil base paint for coating metals or other substrates.

Although the invention has been described in considerable detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for this purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as is set forth in the claims.

What is claimed is:

1. Isocyanato phosphorous compounds having the formula X R as wherein X is selected from the group consisting of oxygen and sulfur, R is selected from the group consisting of O-aryl, O-aralkyl, O-alkaryl, O-cycloalkaryl, S-aryl, S- S-cycloalkaryl, N-(aryl) N-(alkyl) 9 (aryl), N-(alkaryh N-(aralkyl) and N-(cycloalkaryh R" is selected from the group consisting of R, O-lower alkyl, S-lower alkyl and N-(alkyD R is a radical represented by the formula r P n] I wherein Y is a polyvalent radical obtained by removing the active hydrogen atoms from a member selected from the group consisting of polyhydric alcohols and polyamines, z is an integer of from 1 to 2 and corresponds to No references cited. 

1. ISOCYANATO PHOSPHOROUS COMPOUNDS HAVING THE FORMULA 